74 
Dr. Thomson on Oxalic Acid. 
the experiment ; but the result was the same. This induced 
me to combine strontian and oxalic acid in the following 
manner: 100 grains of a solution containing 7 grains of real 
oxalic acid were neutralized by ammonia, and the oxalic acid 
precipitated by means of muriate of strontian. The salt ob- 
tained weighed 12.3 grains ; of course it was composed of 
Acid 7 or 56.9 or 100 
Base 3.3 43.1 75.7 
12.3 100.0 175. 7 
Thus it appears that there are two oxalates of strontian, the 
first obtained by saturating oxalic acid with strontian water, 
the second by mixing together oxalate of ammonia and mu- 
riate of strontian. It is remarkable that the first contains just 
double the proportion of base contained in the second. 
III. Decomposition of the Oxalates . 
1. When oxalic acid, in the state of crystals, is exposed to 
heat, it is only partially acted upon, a considerable portion 
escaping without alteration ; but when an alkaline or earthy 
oxalate is heated, the acid remains fixed till it undergoes com- 
plete decomposition. The new substances into which the acid 
is converted, as far as my experience goes, are always the 
same, what oxalate soever we employ. They are five in 
number ; namely, water , carbonic acid, carbonic oxide , carbureted 
hydrogen, and charcoal . 
2. The water is never quite pure. Though no sensible 
portion of oil can be perceived in it, yet it has always the 
peculiar smell of the water obtained during the distillation of 
wood ; a smell which is usually ascribed to oil. It commonly 
